Valve tip hardening machine and method



Dec. 25, 19354e w, H, SPHRE n SS/ VALVE TIP HARDENING MACHINE AND METHOD Filed Sept. l2, 1951 zo u Ac. 2j

A. 40 KD.C`.

Patented Dec 25, 1934 UNITED STATES yawn TIP HAnDENmG MACHINE AND' METHOD William H. Spire, Cleveland, Ohio, assigner to Thompson Products, Incorporated, Cleveland, Ohio, a corporation of Ohio l Application September 12, 1931, Serial No. 562,482

c claims.

method of, heat treating the tips of the stems of poppet valves, such as are used in internal combustion engines.

The means, and the method, disclosed are not limited in their application to the heat treatment of valve stems, and many other applica- ,Y tions of my invention will readily suggest themselves.

' The tips of that end of a poppet valve stem that engages the valve operating mechanism of internal combustion engines is usually given a nal heat treatment following the mechanical operations that give the valve its form. d

The end of the stem is placed between a pair of opposed electrodes, current is sent through the tip of the stem to raise it to a desired temperature, and then the valve is placed in a quenching bath.

It is obvious that the opposed jaws of the clamping electrodes must be spaced apart to prevent their short-circuiting the path of the current through the clamped valved stem, and it follows that the current flowing from electrode to electrode through the stem will tend to follow one short and relatively narrow pathwith consequent overheating of the metal in that pathdue to the magnetostriction of the current path. The electrodes do not clamp each succeeding specimen in precisely the same way; previous mechanical treatment of the stem. tip variously affects its'conductivity to current, so to produce similar heating effect of the current in the same time would require extraordinary skill on the part of the operator of the machine, and tedious adjustment of the current intensity.

It will be evident that when the major portion of the current, and of the heat energy, flows along a definite and relatively narrow path,the metal in that path will flow and adjust itself within the cross-section of the stem in a manner different from that of the colder metal bordering .cause of the labor involved, the time consumed,

the increased wear of the electrodes and switching mechanism, and the fact that the thermal and electrical conductivity of each succeeding path wasaiected by what happened in previous appliy cations of the current.

It is an object of my invention to provide a machine for imparting heat treatment to the tips of valve stems so that a uniformly good product may be obtained by an unskilled operator.

This invention relates to means for, and the It is also an object of my invention to provide a method of heat treatment which is free of the disadvantages of prior methods.

Other and further important objects of my invention will appear in the description of my invention.

On the drawing:

Fig. i is a schematic diagram of the instrumentalities embodying my invention.

Figs. 2 and 3 are end views indicating heat flow through the end of a heated valve stem during the operation of my machine.

In the drawing:

The numeral i0 indicates, generally, a. conventional step-by-step switch mechanism, which comprises a wiper arm 1i urged forward against a spring i2 by a pawl 13 engaging the teeth of a rachet 15 and actuated by a magnet 14. The

wiper arm successively makes contact with a. plurality of spaced contacts 16. Retraotion of the wiper arm is prevented by a detent i7, and the arm is restored to its original position when thedetent is raised by a releasing magnet 18.

The contacts 16 are extended, or are connected to a row cf contacts i9 so that a manually operated switch 20 may be moved tomake connection with any ci them.

'When the machine is rst put in service to treat a batch of valve spindles, the operator moves selector switch 2c to the zero position in contact with the contact indicated by zero. The wiper arm should then be in its initial position.

The operator now 'closes a foot-switch 2i, thereby causing current to dow from the alternating current supply :mains along wire 22,- through switch 2o, through .wiper arm 1l, along wire 23, through solenoid 24, of switch 25, andr back to -main wire 26. Current flowing through solenoid 24 moves switch 25 to close contacts 27, thereby providing a circuit from wire 22 through solenoid 28, to retract a core 29 thereof, and thereby retract one of a pair of jaws of the electrodes 30, through a connecting link mechanism 3l.

It is a simple matter to arrange things so that both of the jaws are retracted at the same time. and this is usually done.

The tip portion of the stem of a valve 32 is now inserted between the electrodes 30, and the foot-switch 21 is now. opened, whereupon the jaws 30 close to clamp the valve under the urging of a spring 33, or similar means.

The jaws of the electrodes 30 are recessed, as indicated by numerals 34 on Figs. 2 and 3, so that the jaws may readily accommodate themselves to the clamping of round stems of several different diameters, and also to define definite current paths through the cross-section of the stem adjacent opposed margins of the stem.

The operator now moves the selector switch to,

. closes switch 3'?, and thereby energize-s the hectino transformer 4o which is connected to the electrodes 3o. "when the current ows through the electrodes so and the tip of the stem oi' the 'valve 32, the tip becomes heated, and when the tip is viewed from above the two paths of greatest current intensity ore clearly indicated Voir two transverseiy extending white regions with o duller regiou hetoyeeu, as indicated on Fie. 2.

Positioned ahorre the heated stem is a photoelectric oeil ci, or" a conventional type, with e. leus 42 to direct rays from the heated material to its iight-sensitive electrode. The cell 4i suitably connected to a power source through e. conventional amplifier 43, to amplify the current ow oi the cell. Connected to the cell il is a solenoid @i of the switch 39, so that upon the curr through the cell 4l attaining a ypredeter mine ,I indicating a predetermined teruereture oi the heated work, the solenoid to interrupt contacts to, there soieuoid 36, and causing interu ou current.

also causes switch 39 to close its contacts i'i'iereicy establish e. circuit from a direct source, through wire c6, contacts do, magnet le, Wire 17 to advance the arm li. one step iorward.

When the supply circuit oi tronsfomier to is interrupted *ou octioo. of cell Ail, the heut energy iis work ditiuses uniformly over the cross-section ci the materiel, and the whole end takes ou the appearance oi that oi the intere mediate strip o Fig. 2, us is indicatedin Fig. t. -Immediateiy upon this uniform distribution o the heet energy taking place, the current through the cell dl decreases slightly, and in consequence of this courent decrease, switch 39 returns to its ucr-mal position to close contacts 3o and thereby close the circuit through solenoid 3o to close the transformer supply switch 37. The atoremenu tioried croie, choosing the appearance of the heated .trein that indicated iu Fic". 2 to that indicated g. is repeated, with the wiper umn il odvaucins o step when the cell il breaks the heating current through switch 39.,

when the wip arm li has zechiariced to molte coute-ct with. o coutect that is connected to the seiector 2o, circuit is seein closed through 22, wire 23, solenoid 24, to wire 26, to move switch E5 to ciose contacts 27 aud thereiogtf energize solenoid :it to retract en electrode .iets oud Valve SZ tuto a hardening 'com ue operi-ttor inserts euother velue he ttf/ceu the ouen issus, then momentarily re ieeses the foot switch 2l to de--ecergice a soleuoid Lit, connected joaraiiel with wies 22 aud to reiecse switch 5o, to close contacts 5l,

" it' u circuit through the det und wires ed und 4f". "l

Atu the the method which comprises the steps rocosos wiper arm li returns its original position, and now, without any effort oi the operator other than to tzeep the foot switch 2l closed, the uic.- chiiie automatically gives the stem. the desired number of heat cycles and then drops the vulve relays to obtain orly reasonable variation iu the heat application and' heat flooding periods to properly treat stems of different diameters of different izoalterials.

lt will he understood that the conventional step-by-step mechanism described he ifs-ri ously modified while retaining, in substance, its function in causing interruption of the current ut the end of a predetermined number oi? heating cycles.

When u hatch of material, comprises stems or rods which are substantially alike iu their history oi previous treatment, in diameter, and iu composition, o. given number ci? heating cycles usually talespiace in o. fairly deirute period oi' time, so it would theo. se 'possible to arrange things so that heating current is interrupted and the jews opened to drop the rod or stern the end oi a certain. period foliowing the closing of the ij'oot switch.

Tl am aware that muuy changes may' ce made and. luuu'uerous details u* construction "y be varied through Wide from the principles oi' t tore, do not purpose limiting the r .i hereon otherwise than necessitated oy the art.

li claim:

1. The method oi heat treating automotive en eine Valve stems ci which the tip thereoi1 is port oi' an electric heating circuit to produce cycles .f

oi heating of high intensity arid diiusion of heat in the tip during the heat treatment, which comprises the steps of applying timed and alternatM ing applications of current of one intensity,T and then oi' another intensity through the metal in rapid succession to produce periods ot heating and of heat idusiou iu the tip by means responsive to predetermined and alternating; chooses of tem pcrature of the metoi, und .for a predetermi. uuroher ci cycles.

2. lu the heat treating an automotive en eine vulve oi which the tio thereof is port oi au electric heating circuit to produce cycles of heating ci h intensity sud of heut c?" i us r circuit to produce 

